Wood-screw



(No Model.)

G. T. CHAPMAN.

WOOD SCREW.

No. 449,037. Patented Mar. 24, 1891.

Invader;

. UNITED STATES PATENT OFFICE.

GEORGE T. CHAPMAN, O F IVHITE PLAINS, NEIV YORK.

WOOD-SCREW..

SPECIFICATION forming part of Letters Patent No. 4A9,03'7, dated March 24, 1891.

Application filed July 23, 1890. Serial No. 359,590. (No model.)

which are to strengthen the head against the tendency of breakage by the screw-driver and so that it will retain the filling of putty generally applied in finishing interior Work more effectually, all as hereinafter fully described, reference being made to the accompanying drawings, in Which- Figure 1 is a side elevation of a wood-screw constructed in accordance with my invention, and Fig. 2 is a top view.

I make the nick (t wider below the surface of the head than thereat and curved from side to side at the bottom, said curve being preferably on a greater radius than the half of the width of the nick at the top. The nick of this form may be produced in any approved Way, as by first sawing the nick in the usual way the width of the top, but with a saw having a suitablycurved edge, and then, while the head of the screw is confined in suitable dies, punching out the wider porbottom of the nick, because it distributes the stresses over the whole of the curved sur' face, while in the angular form the stresses are concentrated in the angles, so that the head is much Weaker and breaks in many cases where it will notas I have constructed it.

The advantage of this form of nick for retaining putty in inside'work is obvious. If necessary, I will case-harden the head .to prevent the edges of the nick from being jammed or upset by the pressure of the screw-driver.

I claim I The improved wood-screw having a nick wider below the surface of the head than thereat and curved from side to side in the bottom, substantially as described.

In testimony that I claim the foregoing as my invention I have signed my name, in presence of two witnesses, this 26th day of April, 1890.

GEO. T. CHAPMAN.

Witnesses:

W. J. MORGAN, W. B. EARLE. 

